The pain is an unpleasant discomforting sensation caused by injury or disease. Depending on the cause the pain may be acute onset or chronic in nature.
The word pain comes from the Latin poena which stands for punishment, as it was considered punishment from Gods.
Pain occurs very frequently in the people and often signifies an underlying symptom. Thus pain is a syptom in itself and is not a condition per se.
Pain is a common cause of a visit to the physician or pain specialists.
Definition of Pain
Pain is defined as a perception of the signals by the body about occurring or potential tissue damage. Pain can be perceived through the small sensory nerve endings or specialized structures.
There are many chemical processes involved in pain perception. For example prostaglandins. The processes of the perception are called nociception. There are many mechanisms involved in nociception.
The nociception involves a complex interaction of the peripheral and central nervous systems.
The receptors generate an electrical impulse that travels to the spinal cord which acts as a relay center. The spinal cord is involved in blocking, enhancing or modifying the signal before the signal is forwarded to the brain.
It involves an interplay between neurotransmitters which are responsible for the transmission of nerve impulses from one cell to another. The pain transmission is also linked to the emotional centers in the brain.
Thus our emotions affect the pain. Our feelings like anger, anxiety increase it and positive feelings like happiness make it less.
Classification of Pain
Acute and Chronic
Acute and chronic pains are classified on the basis of onset time.
Acute pain is of recent onset. For example, ankle sprain will cause acute pain. This kind of pain occurs suddenly and generally is expected to be over soon.
A pain that continues for a period of several months or longer, or occurs frequently for months is termed as chronic. Back pain or arthritis are examples.
Nociceptive, Neuropathic, or Psychogenic Pain
Nociceptive
It is the pain caused by ongoing activation of pain receptors in either the surface or deep tissues of the body. It is of two types – somatic and visceral
Examples are an injury to skin, muscles, bone, joint, and connective tissues.
Visceral pain originates from injury to the visceral organs like gallbladder, intestine, lungs etc. or the tissues that support them. It is poorly localized and cramping or could be pressure-like, deep, and stabbing in case of nonhollow organs.
Neuropathic
This type of pain continues even after the injury has healed and believed to be caused by changes in the nervous system.
The cause could be trauma or diseases like diabetes. Diabetic neuropathy and complex regional pain syndromes are few examples.
Psychogenic
The term is used for all kinds of pains where the cause can be attributed to psychological problems. Most patients with chronic painful conditions have some degree of psychological issues like anxiety or depression.
Therefore patients with chronic painful conditions should be assessed for psychological factors, and psychological treatments should be considered an important aspect of pain therapy.
Diagnosis
The exact measurement of pain is not possible. In spite of medical advances, there is no test to measure intensity, no imaging device can show pain, no equipment for localization.
Functional MRI [fMRI] of the brain is being tried to measure pain, giving good correlations with self-reported pain.
The pain can be gauged by using many scales made for this purpose. FACES and VAS have frequently used scales for gauging the severity.
During history, a patient tells about the type, duration, and location of the pain. The characteristics of the pain as described by the patient e.g. sharp or dull, constant or intermittent, burning or aching may give the best clues to the cause.
The aim is to find out the underlying cause and provide treatment accordingly.
The investigations of a case of pain would depend on the presentation, site of the pain, and associated symptoms.
These include lab studies and imaging procedures like x-ray, ultrasound, CT scan or MRI, electromyography (EMG), nerve conduction studies, and evoked potential (EP) studies.
Special studies may be done in a few cases. For example, discography to locate painful discs.
Psychological evaluation of the patient may be necessary to identify any psychological issue. Substance abuse should be evaluated.
Treatment
The immediate aim of treatment is to reduce the pain and associated discomfort. Whenever feasible, the underlying cause of the pain needs to be treated.
The pain relief is followed by goal of functional improvement and return to activities of daily living.
When there is acute pain, the drugs for pain are given [analgesics and anesthetics].
- Resting
- Application of heat or ice
- Analgesics
- Nonsteroidal anti-inflammatory drugs- aspirin, ibuprofen, naproxen, acetaminophen etc
- Opioid analgesics
- Anesthetic agents in selected cases
Management of chronic pain is more complex. It may involve more than one medical specialties and precautions on the part of the patient.
Apart from above-mentioned choices, a secondary line of treatments may include medications, nerve blocks, biofeedback, steroid injections, anticonvulsants, and behavioral therapy
Drug Used for Pain Relief
Analgesic Drugs
This group includes both opioid drugs like buprenorphine, tramadol, and nonsteroidal anti-inflammatory drugs like aspirin, acetaminophen, and ibuprofen etc.
Nonsteroidal anti-inflammatory drugs act at the level of peripheral pain receptors, opioid drugs act at the central level to decrease the perception of painful stimuli.
Anticonvulsants
Carbamazepine, in particular, is used to treat a number of painful conditions, including trigeminal neuralgia. Gabapentin also has a role in neural pains.
Antidepressants
Antidepressants or psychotropic drugs and anti-anxiety drugs are sometimes used along with analgesics selected cases where simple analgesic therapy is not effective.
Local Applicants
Irritants like capsaicin work by increasing blood flow to the skin when applied locally. Increased blood flow provides warmth and sense of pain relief.
Antimigraine Drugs
Sumatriptan, naratriptan, and zolmitriptan and are used specifically for migraine headaches.
Steroids
Steroids are potent analgesics and antiinflammatory agents. In musculoskeletal problems, intralesional streoids are often used to provide pain relief.
Biofeedback
These therapies are used for unrelenting back pains and headaches.
The patient uses an electronic machine to become aware of, to follow, and to gain control over certain bodily functions, including muscle tension, heart rate, and skin temperature. The individual can then learn to effect a change in his or her responses to pain by using relaxation and other techniques.
Cognitive Behavioral Therapy
There is always a cognitive element of the pain and patient can be made to learn coping skills and relaxation methods to cope with pain.
This method is used for postoperative pain, cancer pain, and the pain of childbirth.
Counseling and support groups can also help patients.
Electrical stimulation
Electrical stimulation can be given by various methods and each requires specialized equipment and trained personnel.
TENS
It uses tiny electrical pulses, delivered through the skin to nerve fibers, numbness or contractions in the muscles and in turn, produces temporary pain relief.
Peripheral Nerve Stimulation
Electrodes are placed surgically on a carefully selected area of the body using a remote device, the patient can deliver an electrical current as needed.
Spinal Cord Stimulation
Electrodes are surgically inserted within the epidural space of the spinal cord. The patient is able to deliver a pulse of electricity to the spinal cord by using a device.
Deep brain stimulation
Surgical stimulation of the brain, usually the thalamus is used for a limited number of conditions, including severe pain, central pain syndrome, cancer pain, phantom limb pain, and other neuropathic pains.
Nerve Blocks
This method is used to interrupt the relay of pain messages between specific areas of the body and the brain. The procedure could be done surgically drugs.
Neurectomy, trigeminal rhizotomy, and sympathectomy are few examples.
Physical Therapy and Rehabilitation
Light to moderate exercises such as walking or swimming-can contribute to well-being, can help reduce stress, thereby helping to alleviate pain.
Local Therapies
RICE therapy stands for rest, ice, compression, and elevation. RICE therapy is being prescribed for temporary muscle or joint conditions, such as sprains or strains o rin setting of acute injury.
Surgery
Surgery is usually last resort if feasible and the option cannot be exercised in all kinds of pain.
Few examples are discectomy, joint fusion, ingrown toenail removal etc.
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